A reciprocating saw machine is a power saw, often hand held, including a chuck that releasably engages one end of a reciprocating saw blade (i.e., a tang on the inner end of the saw blade) and drives the inner end, and thus the saw blade, in a back and forth reciprocating motion through a work piece. Reciprocating saw machines are typically driven by electric motors (e.g., cord or cordless saws), or are pneumatically driven. The reciprocating motion can be an orbital cutting action, a straight or linear cutting action, or an angled cutting action. Reciprocating saws are sometimes referred to as recip saws, or jig saws, and reciprocating saw blades are sometimes referred to as recip blades or jig saw blades. A jig saw includes a handle and a relatively small, thin blade oriented to be used comfortably on horizontal surfaces. A recip saw usually has a larger blade and blade-mounting assembly resembling that of a jig saw, but includes a handle oriented to allow the saw to be used comfortably on vertical surfaces. Well known reciprocating saws are sold under the brand names “SAWZALL™” by Milwaukee Electric Tool Corporation and “TIGER SAW™” by Porter-Cable Corporation.
Some reciprocating saw machines also include a shoe attached to the front end thereof, having a central opening through which the saw blade extends. The shoe is adapted to engage a work piece during cutting to stabilize and guide the reciprocating movement of the saw blade into an out of the work piece.
A reciprocating saw blade for use in a reciprocating saw is typically elongated having a length selected for a particular cutting application. As mentioned, the inner end of the blade defines a tang for releasably mounting the blade in the chuck of a reciprocating saw, and the outer end of the blade is a free end that engages a work piece. Some recip blades, however, have tangs on both ends, such as described in U.S. patent application Ser. No. 12/396,318, filed Mar. 2, 2009, entitled “Reciprocating Saw Blade with Tangs on each End and Related Method,” which is hereby expressly incorporated by reference in its entirety as part of the present disclosure. Typical reciprocating saw blades include a cutting edge, extending between the inner and outer ends of the blade, defined by a plurality of cutting teeth spaced relative to each other along one side of the blade or some other cutting medium. Often, a non-working edge is formed on an opposite side of the blade relative to the cutting edge. Some blades, however, have two opposing cutting edges, such as described in U.S. patent application Ser. No. 13/344,647, filed Jan. 6, 2012, entitled “Double-Sided Reciprocating Saw Blade and Related Method,” which is hereby expressly incorporated by reference in its entirety as part of the present disclosure.
A reciprocating saw blade relies, in part, on its tang angle for its effective cutting action. The tang angle is the angle between the tang and the cutting edge. A positive tang angle increases the cutting angle of the blade. An increased cutting angle generally provides more aggressive cutting action and thus quicker cutting. However, increased cutting angle requires more power to start or continue the cut, and can affect wear and/or durability of the blade. Large cutting angles can also result in high and even excessive vibration transmitted to the user, resulting in a poor end user experience that is described as a “rough feel” when using the blade. Therefore, where the design of the cutting portion of the blade and/or the material to be cut can implicate these effects, tang angle is selected so that the cutting angle of the blade does not exceed an acceptable amount.
Another factor limiting the magnitude of a blade tang angle is the shoe of the saw machine. The tang angle of the blade must be small enough so that the blade will not interfere with, or cut into, the shoe while reciprocating through the central opening thereof, thereby damaging the shoe and also unnecessarily increasing blade wear.
Yet another factor that limits the magnitude of the tang angle is that as the tang angle increases the proximal end of the tang comes closer to the tooth edge. As many recip saw blades are punched from continuous toothed strip the proximal end of the tang may intersect the gullets of the teeth in the strip. This is undesirable because it reduces the life of the punching dies and also creates a discontinuous, notched surface along the tang that the end user will regard as a product defect. Thus, it may not be practical or possible to provide a tang angle to achieve a desired effective cutting angle.